i have no idea how to fully script this. in my mind, it'll be semi-scripted because some of the things which the chefs say will be as they do the demo and some of what they say will be required.
is the food network scripted? hardly! some of it is rehearsed, but most of it (including camera positions) is made up.
Not to jump on you to hard, but Food Network and most cooking shows are meticulously scripted. They have an extensive department of "culinary producers" who's main task is to script the movement of recipes.